This invention relates to electronic systems having a backplane for supporting plug-in modules wherein a signal is daisy-chained through the modules and, more particularly, to an arrangement in such a system for bypassing the daisy-chained signal when a module is absent from its assigned "slot" on the backplane.
Many electronic systems, such as computers, have a backplane (or mother board) on which are mounted connectors defining slots into which plug-in modules (or daughter cards) may be demountably secured. The backplane provides wiring (i.e., printed circuit traces) to effect communications between the modules and to provide a supply of power to the modules. Many such systems include a signal line on the backplane for carrying a daisy-chained signal through all of the modules present in the system. Since a given slot may or may not hold a module, some means must be provided for bypassing the daisy-chained signal around an empty slot and passing the daisy-chained signal through the slot when a module is present therein. Accordingly, it is an object of this invention to provide an arrangement for effecting such selective bypass function.
It is known to provide the selective bypass function by using manual or mechanical jumpering schemes. However, such schemes have proven to be unreliable. It is therefore a further object of this invention to provide a selective bypass arrangement which utilizes reliable non-mechanical devices.